In general, since batteries such as lithium ion batteries or nickel hydrogen batteries use valuable materials including rare resources such as cobalt and nickel, when there is a need for disposal because the service life of a battery itself has ended or a battery has been judged to be defective in the production process, batteries are collected, and recycled. Regarding the method for recovering valuable materials from wastes batteries, various methods have been suggested hitherto, and examples thereof include a method of separately recovering various valuable metals by roasting waste batteries, and a method which enables recovery of various valuable metals as well, as recovery of various members such as an organic electrolyte solution, by disassembling waste batteries.
However, in the former method, recovery of valuable materials that are flammable is impossible. Furthermore, in the latter method, if a large amount of charge is remaining in waste batteries, short circuit occurs at the time of disassembling, and there is a risk of explosion or the like. It is desirable if the recovery of valuable materials from waste batteries can be carried out safely. Thus, in order to solve such problems, a method has been suggested for discharging waste batteries in advance before disassembling by immersing the waste batteries in a liquid having conductivity.
For example, Patent Document 1 discloses a method for discharging waste batteries by immersing the waste batteries in an aqueous solution having a weak acid salt of an alkali metal, dissolved therein.
[Patent Document 1] Japanese Unexamined Patent Application, Publication. No. 2005-347162